The invention relates to a side channel pump for supplying liquid and gaseous fluids as well as mixtures of liquid and gas.
Among other things, side channel pumps are used for generating a vacuum. From EP-A-0 170 175, a side channel vacuum pump is known that includes several annularly extending pump channels limited by the rotor and by the stator each. At the rotor, blades are arranged, protruding into the respective pump channel cross-section. From radially inside, the blades protrude only into a portion of the pump channel cross-section so that the radial outer portion of the pump channel is free of blades. The blade-free portion of the pump channel is the side channel.
During rotation of the rotor, the fluid molecules are seized by the blades and accelerated in circumferential direction. Due to the centrifugal force, the fluid molecules are moved outward into the blade-free side channel. In the side channel, the radially outward directed movement is again deflected radially inward in the direction of the blades, the fluid molecules being strongly braked again by the friction at the fixed stator wall. The fluid molecules leave the side channel in a radially inward direction and are seized by the blades again and accelerated in circumferential direction. Through this continuously repeating process, a circumferentially moving helical fluid whirl develops in the pump channel.
The fluid inlet and the fluid outlet are formed by a stop wall radially protruding from the stator into the blade-free cross-sectional area of the side channel. In the region of the stop wall, the incoming fluid flow passes out of the blade-free cross-sectional area of the pump channel to a fluid outlet. The portion of the fluid in the region of the blades at that time is not seized by the stop wall and is therefore entrained by the blades to the fluid inlet at the rear side of the stop wall.
The compressed fluid entrained to the suction side expands again to the suction pressure on the suction side and is compressed again. This means that, in the region of the blades, the pump channel forms a short circuit between the pressure side and the suction side of the annular-like pump channel. The pressure losses caused in this manner produce heating and noise. In a vacuum pump, several such annular pump channels are connected in series or combined with another molecular pump stage, with a turbomolecular pump stage, for example, for generating high degrees of compression. Because of their simple mechanical structure, ease of maintenance, and reliability, side channel pumps are well suited for industrial use. Due to the plurality of loss-inflicted fluid inlets and outlets, however, the suction capacity and the compression ratio are limited.
The present invention contemplates an improved apparatus and method that overcomes the aforementioned limitations and others.